In anemometers it is conventional practice to employ a rotor defined by a series of wind cups mounted on spokes which radiate from a common hub, the hub being secured to a shaft or spindle which projects from a sutiable airborne atmospheric testing device. Typically, the cups are so mounted that an axis through each cup is arranged perpendicular to the longitudinal axis of the hub, the cups being highly sensitive to air or wind speed so as to rotate at a rate corresponding to wind speed. This rotation is then transferred through the shaft into the sensing instrument and figured into various atmospheric calculations.
In the construction of the anemometer, it is highly desirable that the rotor possess perfect balance and alignment such that the cups are aligned in a common horizontal plane and can be simply fabricated, such as, by molding. However, molding a series of cups and connected spokes with a common hub can be quite expensive and time-consuming. Moreover, if one of the cups or the connected spokes should become broken it would require replacement of the entire assembly. In the past, rotor assemblies have been devised in which the cups are formed unitarily with spokes, the spokes being pivotally connected by links to a spider plate, such as, disclosed by U.S. Pat. No. 4,102,188 to R. A. Simerl. Another approach to rotor construction is illustrated in U.S. Pat. No. 3,020,963 to W. Hakkarinen in which each cup has a securing band riveted to an arm of a spider plate with the entire structure reinforced by one or more rigid rings secured above and below the cup. U.S. Pat. No. 3,897,170 to A. Darvishian discloses a wind motor construction for conversion of wind power to other usable forms of power wherein cups are pivotally mounted on arms fastened by collars to a central shaft. However, the cups are arranged to rotate in different horizontal planes which is not practical for use in an anemometer assembly where, among other criteria, it is important that there be optimum balance and alignment of the cups in a common plane. Representative of other approaches in the construction of anemometer devices are U.S. Pat. No. 3,699,801 to J. I. P. Jones and U.S. Pat. No. 2,259,615 to R. R. Chappell et al.